The present invention relates to a near-field optical head, and more particularly, and to a near-field optical head in which near-field microscope technology is applied to a head of a recording apparatus represented by a hard disk or the like.
According to a near-field microscope provided with an optical probe utilizing near field light, a sample can be observed with a high resolution equal to or higher than a diffraction limit of light. According to such a near-field microscope, as an end portion of the optical probe opposed to a sample, there is used a very small aperture provided at a sharpened distal end of an optical fiber or a very small aperture provided at a tip of a silicon substrate which is formed by carrying out anisotropic etching or there is used a very small protrusion constituted by the sharpened distal end of the optical fiber or on the tip.
Meanwhile, there has been proposed a near-field optical memory disclosed in, for example, E. Betzig et al., Science 257, 189 (1992), to which such an observation principle is applied. According to such an example of application, a very small aperture or a very small protrusion formed at a recording or reading head needs to be proximate to a surface of a record medium or to be brought into contact with the surface within a wavelength of illumination light which is propagating light.
In many cases of a recording/reading system of a near-field optical memory, a record medium in a disk-like shape is rotated and a surface thereof is scanned by a head. Therefore, in accordance with rotation of the record medium, vibration is caused in an in-plane direction of a principal face (direction in parallel with the principal face) and in an out-of-plane direction (direction orthogonal to the principal face). In a recording/reading system, a head and a surface to be detected need to be proximate to each other and therefore, the vibration in the out-of-plane direction becomes important. The vibration in the out-of-plane direction is mainly caused by flatness of the principal face of the record medium, accuracy of attaching the record medium to a rotating shaft and accuracy of a bearing of the rotating shaft. Meanwhile, on the side of the head, the very small aperture or the very small protrusion needs to follow the vibration in the out-of-plane direction of the record medium.
Generally, according to a recording/reading system of a near-field optical memory, there is used a head adopting a cantilever structure having a very small aperture or a very small protrusion, when the head is operated by a contact AFM (Atomic Force Microscope), a distance detecting mechanism is needed for detecting bending of the cantilever, or, when the head is operated by cyclic contact or shear force, a distance detecting mechanism is needed for detecting a change in the frequency, an amplitude and a phase of vibration or the like. Further, there are needed a feedback circuit for feeding back a detected signal thereof and a distance changing mechanism for actively changing an interval between the cantilever and the record medium based on the feedback signal.
However, according to the above-described conventional recording/reading system of the near-field optical memory, the distance detecting mechanism, the feedback circuit and the distance changing mechanism are necessary and, therefore, there poses a problem of complicating the construction of the recording/reading system.
Hence, the invention has been carried out in view of the above-described drawbacks in the conventional art and it is an object thereof to provide a near-field optical head which a simple structure and which is capable of simplifying control of a distance between a record medium and a head.
In order to achieve the above-described object, according to an aspect of the invention, there is provided a near-field optical head characterized in comprising a slider supported by a suspension arm for providing a load, exerting a fly force by a movement thereof relative to a record medium and producing a clearance between the slider and the record medium by balancing the load with the fly force, and a cantilever extended from the slider and having a very small protrusion or a very small aperture at an end portion thereof, wherein the very small protrusion or the very small aperture is brought into contact with the record medium by flying and inclining the slider.
The near-field optical head uses a flying-head mechanism and, therefore, an active distance controlling mechanism in respect of the record medium is dispensed with. Further, by utilizing the near-field light, a resolution equal to or higher than a diffraction limit of light is achieved, there is adopted a system of bringing the very small protrusion or the very small aperture in contact with the record medium and, accordingly, fine data can be recorded and reproduced and a transmission rate of data is increased.
Further, according to another aspect of the invention, there is provided a near-field optical head characterized in comprising a slider supported by a suspension arm for providing a load, exerting a fly force by a movement thereof relative to a record medium and producing a clearance between the slider and the record medium by balancing the load with the fly force, and a cantilever having a very small protrusion or a very small aperture and extended from the slider such that when the slider is brought into a state of being in contact with the record medium, the very small protrusion or the very small aperture is brought into a state of being not in contact with the record medium, wherein when the slider is flown and inclined, the very small protrusion or the very small aperture is brought into contact with the record medium.
The near-field optical head uses the flying-head mechanism and, accordingly, an active distance controlling mechanism in respect of the record medium is dispensed with. Further, by utilizing near-field light, a resolution equal to or higher than a diffraction limit of light is achieved, there is adopted the system of bringing the very small protrusion or the very small aperture in contact with the record medium and, accordingly, fine data can be recorded and reproduced and the transmission rate of data is increased. Further, only when the slider is made to fly, the very small protrusion or the very small aperture is brought into contact with the record medium and is not brought into contact therewith in a stationary state and, accordingly, the very small protrusion or the very small aperture can effectively be protected.
Further, according to another aspect of the invention, there is provided a near-field optical head characterized in comprising a slider supported by a suspension arm for providing a load, exerting-a fly force by a movement thereof relative to a record medium and producing a clearance between the slider and the record medium by balancing the load with the fly force, and a cantilever having a very small protrusion or a very small aperture at an end portion thereof, extended from the slider and providing a height difference between the very small protrusion or the very small aperture and a bottom face of the slider, wherein when the slider is flown and inclined, the very small protrusion or the very small aperture is brought into contact with the record medium.
According to the near-field optical head, the flying-head mechanism is used and, accordingly, an active distance controlling mechanism in respect of the record medium is dispensed with. Further, by utilizing near-field light, a resolution equal to or higher than a diffraction limit of light is achieved, there is adopted the system of bringing the very small protrusion or the very small aperture into contact with the record medium and, accordingly, fine data can be recorded and reproduced and the transmission rate of data is increased. Further, by providing the height difference between the very small protrusion or the very small aperture and the bottom face of the slider, only when the slider is flown, the very small protrusion or the very small aperture is brought into contact with the record medium. Therefore, the very small protrusion or the very small aperture can effectively be protected.
Further, according to another aspect of the invention, there is provided a near-field optical head characterized in comprising a slider supported by a suspension arm for providing a load, exerting a fly force by a movement thereof relative to a record medium and producing a clearance between the slider and the record medium by balancing the load with the fly force, a cantilever extended from the slider and having a very small protrusion or a very small aperture at an end portion thereof and a moving mechanism for moving the slider in a direction orthogonal to the record medium, wherein the very small protrusion or the very small aperture is brought into contact with the record medium when the slider is made to approach the record medium by the moving mechanism and is made to fly.
The near-field optical head uses the flying-head mechanism and, therefore, an active distance controlling mechanism in respect of the record medium is dispensed with. Further, by utilizing near-field light, a resolution equal to or higher than a diffraction limit of light is achieved, there is adopted the system of bringing the very small protrusion or the very small aperture into contact with the record medium and, accordingly, fine data can be recorded and reproduced and the transmission rate of data is increased.
Further, according to another aspect of the invention, there is provided a near-field optical head characterized in comprising a slider supported by a suspension arm for providing a load, exerting a fly force by a movement thereof relative to a record medium and producing a clearance between the slider and the record medium by balancing the load with the fly force, a moving mechanism for moving the slider in a direction orthogonal to the record medium, and a cantilever having a very small protrusion or a very small aperture and extended from the slider such that the very small protrusion or the very small aperture is brought into a state of being not in contact with the record medium when the slider is brought into a state of being separated from the record medium, wherein when the slider is made to approach the record medium and is made to fly, the very small protrusion or the very small aperture is brought into contact with the record medium.
The near-field optical head uses the flying-head mechanism and, accordingly, an active distance controlling mechanism in respect of the record medium is dispensed with. Further, by utilizing near-field light, a resolution equal to or higher than a diffraction limit of light is achieved, there is adopted the system of bringing the very small protrusion or the very small aperture into contact with the record medium and, accordingly, fine data can be recorded and reproduced and the transmission rate of data is increased. Further, only when the slider is made to fly, the very small protrusion or the very small aperture is brought into contact with the record medium and, is not brought into contact therewith in other state and accordingly, the very small protrusion or the very small aperture can effectively be protected.
Further, according to another aspect of the invention, there is provided a near-field optical head in accordance with the above-described near-field optical head in which the very small aperture is formed at a contact pad provided at the end portion of the cantilever.
At present, there is known a contact system which is conducted by providing a contact pad at a bottom face of a slider (even when the slider jumps, a maximum of 10 nm of a fly amount is provided), and according to the invention, the very small aperture is formed at the contact pad. Particularly, when matching of heights of the front end of the tip and the bottom face of the slider becomes difficult, an effective constitution is constructed. Further, the tip becomes difficult to destruct with a size to a degree of the contact pad. Further, adsorption with the record medium is reduced.
Further, according to another aspect of the invention, there is provided a near-field optical head in accordance with the above-described near-field optical head wherein a plurality of the very small protrusions or the very small apertures are provided, illumination light is divided by using a monochromator and divided portions of the light are irradiated to portions of the record medium in correspondence with the respective very small protrusions or very small apertures.
In this way, when illumination light is divided by using the monochromator, multiplex formation can be constructed by a single light source. Therefore, the head size can be made compact.